Number to String Conversion (format, bases, padding)

Turning numbers into text uses str(n), f-strings f'{n}', bases with format(n, 'b'), or locale-aware formatting. Pick the representation your API contract demands.

Why this shows up in the real world

Receipt printers format currency with fixed decimals. HTTP headers stringify integers for Content-Length and similar fields.

Core idea (explained for students)

Bases: bin(n), hex(n), format(n, '08b') for zero padding. Sign handling: str(-5) includes minus; for custom sign placement build manually.

Try this in Python

def pad_id(n: int, width: int = 6) -> str:
    return f"{n:0{width}d}"


print(pad_id(42), format(255, "08b"))

Common mistakes

• Floating formatting surprises (1.1 binary fraction)—use Decimal for money.
• Leading zeros: str(5) has none; use formatting spec instead.

Key takeaways

• Centralize format helpers (fmt_id(n)) so UI and logs stay consistent.
• Tests should cover zero, negative, and large magnitudes.